Semiconductor device and method of manufacturing the same

Abstract

In a deep trench DTC reaching a predetermined depth from a first main surface of a semiconductor substrate SUB, a plurality of columnar conductors CCB including plugs PUG and field plates FP are formed. A p type impurity layer PIL is formed along the side wall surface of the deep trench DTC. Between the bottom of the plug PUG and the bottom of the p type impurity layer PIL, the field plate FP and the p type impurity layer PIL are positioned to face each other via an insulating film FIF interposed therebetween. Between the bottom of the p type impurity layer PIL and the bottom of the field plate FP, the field plate FP and an n-type drift layer NDL of the semiconductor substrate SUB are positioned to face each other via the insulating film FIF interposed therebetween.

What is claimed is: 
     
       1. A semiconductor device comprising:
 a semiconductor substrate of a first conductivity type having a first main surface and a second main surface opposite to the first main surface; 
 a first electrode formed on the first main surface of the semiconductor substrate; 
 a second electrode formed on the second main surface of the semiconductor substrate; 
 a plurality of columnar conductors formed in the semiconductor substrate and being electrically connected to the first electrode, each of the plurality of columnar conductors extending between the first main surface and a first depth in the semiconductor substrate, the first depth in the semiconductor substrate being measured from the first main surface toward the second main surface; 
 a first impurity region of a second conductivity type formed in the semiconductor substrate and being electrically connected to the first electrode, the first impurity region extending between the first main surface and a second depth in the semiconductor substrate, the second depth in the semiconductor substrate being measured from the first main surface toward the second main surface, the second depth being shallower than the first depth; 
 a second impurity region of the second conductivity type formed in the semiconductor substrate and being electrically connected to the first electrode, the second impurity region extending between the first main surface and a third depth in the semiconductor substrate, the third depth in the semiconductor substrate being measured from the first main surface toward the second main surface, the third depth being shallower than the second depth; 
 a third impurity region of the first conductivity type formed in the semiconductor substrate and being electrically connected to the first electrode, the third impurity region extending between the first main surface and a fourth depth in the semiconductor substrate, the fourth depth in the semiconductor substrate being measured from the first main surface toward the second main surface, the fourth depth being shallower than the third depth; and 
 a gate electrode formed in a gate trench in the semiconductor substrate via a gate dielectric film so as to penetrate the third impurity region and the second impurity region, 
 wherein the first impurity region is in contact with each of the semiconductor substrate of the first conductivity type and the second impurity region of the second conductivity type, 
 wherein each of the plurality of columnar conductors includes a field plate, the field plate extending from a fifth depth to the first depth in the semiconductor substrate, the fifth depth in the semiconductor substrate being measured from the first main surface toward the second main surface, the fifth depth being shallower than the first depth and the second depth and deeper than the third depth and the fourth depth, the field plate and the semiconductor substrate of the first conductivity type being arranged to be opposite to each other via an insulating film, 
 wherein i) a first portion of the field plate extending between the fifth depth and the second depth in the semiconductor substrate and ii) the first impurity region are opposed to each other via the insulating film, 
 wherein, in a region between the second depth and the first depth, i) a second portion of the field plate extending between the second depth and the first depth in the semiconductor substrate and ii) the semiconducting substrate of the first conductivity type are opposed to each other via the insulating film, and 
 wherein a length of a portion of the first impurity region extending from the fifth depth to the second depth in the semiconductor substrate is set to substantially half a length of the field plate extending from the fifth depth to the first depth in the semiconductor substrate. 
 
     
     
       2. The semiconductor device according to  claim 1 ,
 wherein each of the plurality of columnar conductors is formed in a deep trench, the deep trench reaching a portion of the semiconductor substrate of the first conductivity type from the first main surface in such a manner as to penetrate the third impurity region and the second impurity region. 
 
     
     
       3. The semiconductor device according to  claim 2 ,
 wherein each of the plurality of columnar conductors is formed in the deep trench such that each of the plurality of columnar conductors extends between the first main surface of the semiconductor substrate and the fifth depth, and 
 wherein each of the plurality of columnar conductors includes a plug contacting the field plate and the first impurity region. 
 
     
     
       4. The semiconductor device according to  claim 1 ,
 wherein the first impurity region includes a first portion having a first impurity concentration and a second portion having a second impurity concentration higher than the first impurity concentration, and 
 wherein the second portion of the first impurity region is located on a near side of the first main surface than the first portion of the first impurity region. 
 
     
     
       5. The semiconductor device according to  claim 1 , wherein the semiconductor substrate of the first conductivity type includes a first layer having a third impurity concentration and a second layer having a fourth impurity concentration lower than the third impurity concentration,
 wherein the second layer is located closer to the first main surface than the first layer, and 
 wherein each of the plurality of columnar conductors is formed to reach the first layer, and the gate electrode is formed to reach the second layer. 
 
     
     
       6. The semiconductor device according to  claim 1 , wherein each of the plurality of columnar conductors has a shape of any one of a square, a circular, or an octagonal in a plan view.